Is foot drop common after disc prolapse and how to treat it?
Q: My husband has been diagnosed with foot drop and the MRI report of the Lumbosacral Spine is as follows: the inter-vertebral disc between L4-L5 shows alteration in signal intensity denoting degenerative dehydration; this is associated with circumferential annular bulging as well as a mild posterior right paracentral disc protrusion causing indentation on the right L5 nerve root sheath in the spinal canal and indentation on the right side of the ventral aspect of the thecal sac. The disc between L5-S1 shows degenerative dehydration with mild circumferential annular bulging causing indentation of the epidural fat as well as indentation of the ventral aspect of the thecal sac with slight indentation on the anterior aspects of both exit foramena. Early degenerative dehydration of the disc between L3-L4 associated with a slight bulging mildly indenting the thecal sac. Some straightening of the lumbar lordosis in favour of muscle spasm. Normal signal intensity of the vertebral bone marrow for the patients age. Normal looking Conus medullaris and nerve roots of the Cauda Equina otherwise, the other lumbar intevertebral discs show normal height and normal signal intensity. Impressions: - Degenerative dehydration with annular bulging of the disc between L4-L5 associated with mild posterior paracentral protrusion indenting the right sight of the thecal sac and the right L5 nerve root sheath in the spinal canal. - Mild degenerative bulging of the disc between L5-S1 mildly indenting the theca and both exit foramena. - Mild Bulging of the disc between L3-L4. - Evidence of muscle spasm. Foot drop occurred after few days of the 1st MRI report. The second report said: There is still right posterior protrusion of the disc between L4-L5 which is almost the same or very slightly more than what was seen one month ago, associated with indentation on the right L5 nerve root sheath as well as on the right side of the ventral aspect of the thecal sac as seen in MR Myelogram. Similar changes also noted in the discs between L5-S1 and L3-L4 namely of disc dehydration and circumferential mild annular bulging. Some straightening of the lumbar lordosis in favour of muscle spasm. I want to know what are my options of treatment, is surgery necessary?
A:Foot drop can be secondary to a large disc prolapse at L4-5 level. This prolapse must be sufficient enough to call significant pressure on the nerve root. Mere presence of disc on the MRI at that particular level is not sufficient evidence for intervention. An orthopaedic surgeon or a neurologist needs to examine to confirm that the foot drop is indeed as a result of disc bulge and not because of a nerve lesion in the leg. Assuming the diagnosis of the disc is right, surgery for removal of the disc may not correct the foot drop. Usually once foot drop occurs it tends to persist. Therefore, surgery for disc is not done expecting recovery of foot drop but it is done to prevent further damage and pain radiating to the legs. The foot drop itself can be treated surgically by doing a tendon transfer. This surgery can be done at any stage by an orthopaedic surgeon experienced in tendon transfers. Therefore, do get in touch with an orthopaedic surgeon with such skills in your neighbourhood.